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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Monday, February 11th 2013
Created: Feb 11th 5:54 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
The Bottom Line

The avalanche hazard is MODERATE above treeline and in open areas below treeline that were affected by the high winds from Saturday.  Lingering pockets of dense wind slab 1-2 feet thick are resting on a layer of lighter density snow above treeline and a slick crust in open areas below treeline.  The avalanche hazard is generally LOW below treeline except for in isolated pockets that received wind loading over the weekend.


Primary Concern

Sustained 40-60 mph winds on Saturday (two days ago) helped to form large dense wind slabs in many areas.  Most of the new snow that fell over the weekend is well bonded to the old snow surfaces.  In areas that received wind loading this bonding is not as good and it is easy to find "upside down" snow on ridgelines, in starting zones and above cross loaded gullies.  While these slabs have been reluctant to move under the weight of a snowmachine or skier, they still warrant respect, as they are large in size and able to do damage to a person once released.  Avoiding starting zones above 35 degrees, wind affected snow above terrain traps and isolated areas below treeline that have these slabs will be your best bet today.


Secondary Concern

The winds and snow that formed wind slabs over the weekend also helped to increase the size of cornices.  Always give cornices a very wide berth.  When approaching from below try to envision what would happen if that cornice you're looking up at came towards you.  When traveling above cornices in the higher elevations, always avoid the edge.  If you can't see what is below you or a cornice is looming above you it's probably time to back off.  Try to view cornices from the side to see where the ground is and where the snow is overhanging & unsupported.  Heating from the sun combined with an absence of wind could increase the likelihood of cornices releasing today.

 

 

Additional Concerns

Loose Snow Avalanches

Several inches of light density snow will be found on the surface today.  The potential for relatively small shallow loose snow avalanches exists.  These will become a greater problem in steeper terrain.  Avoiding these surface slides in steep terrain above cliff bands and gullies will help to minimize your exposure to this hazard.

Deep Slabs

We are still monitoring the weak snow at the base of the snowpack that formed in the first part of the season.  Above 2,000 feet and in areas with less overall snow this problem is more pronounced.  While it is unlikely to trigger a deep slab today, it can't be ruled out.  Assess the terrain you are on and ask yourself some questions.  What is the overall snow depth?  Are there potential trigger points where the snow is shallow?  Continuing to follow good travel habits, i.e. only putting one person at a time on a slope and using true islands of safety will help to mimimize your exposure to this problem.


Mountain Weather

The mountains around Turnagain Pass have picked up 2-4" of new snow with .2-.3" of water in the past 24 hours.  The Girdwood Valley has had up to 6" of new snow with .3-.6" of water.  Winds at 3,800' have averaged in the high teens out of the E and SE and temperatures have been in the low 20s F.

Veering winds have slowed down this morning and temps are on the decline.  Light snow is falling at sea level.  

Snowfall will taper off this morning.  Ridgetop winds will be light, blowing 10-15 mph out of the W and NW.  Temperatures at 1,000' will be around 30 degrees F and skies will be clearing through the morning hours.

The next chance for snow will come tonight and into tomorrow morning, with generally low amounts expected.

________________________________________________________

Graham will issue the next advisory tomorrow morning February 12th.

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: May 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
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